Wireless communication has repeatedly proven and extended its usefulness since its earliest days, and as time has passed the technology has steadily improved. The improvement of the technology has made wireless communication widely available. The systems required have become smaller, consuming less power, and they have come to require less skill to operate. While early systems required a large assembly consuming substantial power, and required the operator to be able to transmit and receive in Morse Code, a present day wireless communication user need do no more than pull a communication device such as a cellular telephone out of his pocket, press a sequence of keys, and begin to communicate.
Progress toward universality of wireless communications is today exemplified by the cellular telephone network. With a cellular telephone, a user can communicate with other cellular telephone users or with conventional telephone users from a wider and wider geographic range, because of the large number of repeater stations in the cellular network.
Cellular telephones have advanced immensely since their introduction. They have become much smaller, and have become capable of digital data transmission as well as voice transmission. The additional features and small size have come with a cost, however. Adding additional features to a cellular telephone increases its complexity and cost, and tends to increase its size. Reducing the size of cellular telephone is presently accomplished through the development and use of highly miniaturized components. The use of such miniaturized components adds greatly to the cost of a device. Moreover, the substantial power requirements of cellular telephony limit further reductions in the size and weight of a battery-operated telephone because of the requirement that the battery be able to provide a certain amount of power. The power requirements of conventional cellular telephones require the battery to be a certain size, or alternatively, require the use of new and more expensive battery technologies, or else limit the length of time the telephone can be used without recharging or replacing the battery.
Other features of conventional cellular telephones include the ability to dial any number, as does an ordinary land-based telephone, to display the number being called and the various features being selected, and the ability to send and receive fax and data transmissions. All these features add to the expense and complexity of the cellular telephone. A less expensive and less complex phone is highly desirable for many users and applications.
Moreover, applications exist in which a cellular telephone with limited function would be highly desirable. An employer may wish to give a limited capability cellular telephone to a courier, for example, with which the courier could call a central office, or a parent may wish to give a child a cellular telephone with which the child can call home. The same features that add to the weight, complexity and expense of present-day cellular telephones also increase the risk of giving cellular telephones to employees or children, by allowing the employer or child to incur the expense of calling locations other than a central office or parents' home, respectively. Additionally, the risk of loss or theft of any expensive item is a factor to be considered.
By way of example, the flexibility of a conventional cellular telephone may make it highly attractive to thieves. Conventional cellular telephones can be used by thieves just as easily as by authorized users, and to call any location the thief wishes to call. In order both to discourage theft and to minimize inconvenience and expense to the user which may be caused by theft, one might wish to carry a cellular telephone which was usable only to call a limited range of locations such as one's home, one's office, or a roadside assistance service.
A limited-capability cellular telephone could advantageously achieve added flexibility, while retaining the reduced weight, size and cost occasioned by its reduced capability and the security benefits also occasioned thereby, if it were capable of being programmed at a central location controlled by an authorized user. Such a telephone would not need to be returned to a vendor each time a decision was made, for example, to add or remove callable locations from its inventory.
There exists, therefore, a need in the art for a cellular telephone transceiver which can be readily manufactured at a low size and weight without the need for miniaturization of components, which can be programmed to call only a limited number of calling locations, and whose inventory of calling locations can be reprogrammed by the user at a central location.